In summary, we have demonstrated that the surface plasmon resonance enhancement on the PL spectra of the organic dyes can be achieved. In the study of power dependence, sample A (Znq:DCM), B (BAlq:DCM), and C (Alq3:DCM) show that the PL spectra enhancement is in agreement with the Purcell factor at the major enhanced peak. But since sample D has a fast decay rate before the surface plasmon resonance, the PL spectra enhancement is not consistent with the Purcell factor. In the study of wavelength dependence, we observed that if the initial efficiency is high, the enhancement from surface plasmon resonance is not significant and the influence from the coupling of the surface plasmons can be great when the initial quantum efficiency is low.
Sample A (Znq:DCM) has the largest Purcell factor and the largest surface plasmon recombination rate ( ), and thus shows the largest spontaneous emission coupling factor ( ) and the enhanced efficiency ( ). As the quantum efficiency is increased, so is the spontaneous emission rate. Therefore Znq:DCM can be a promising candidate for further development of a highly efficient organic semiconductor laser.
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